Tobacco containing ten percent nicotine as an insecticide



Patented Dec. 2, 1947 TOBACCO CONTAINING TEN PERCENT NICO- TINE AS ANINSECTICIDE Robert B. Arnold, Richmond, Va., assignor to TobaccoBy-Products and Chemical Corporation, Louisville, Ky., a corporation ofDelaware No Drawing. Application November 14, 1944, Serial No. 563,444

3 Claims.

Nicotine for insecticidal purposes commonly is manufactured and sold tothe consumer in the form of a concentrated solution of nicotine sulfate(about 40% nicotine expressed as alkaloid) and is applied in a varietyof ways such as by simply diluting the solution and spraying it or byabsorbing or distributing the solution upon a finely divided solidcarrier which is applied as such as a dusting powder or in suspension ina liquid as a spray.

A variety of dusting powders containing nicotine have been described inthe literature. Such dusting powders generally contain a relativelysmall percentage of nicotine, say 1 to 4 percent, and are suitable fordirect application to vegetation but are not adapted to be transportedlong distances from the manufacturer to the consumers destination due toexcessive freight cost because of their weightand bulk per unit ofinsecticidal activity.

Prior to my present invention, the need had been recognized for anicotine material of high nicotine content in dry powdered form. Thisneed has been met, in part at least, by the products disclosed in myPatents Nos. 2,219,287 and 2,311,629, an essential ingredient of whichproducts is a combination of a base exchange polysilicate such asbentonite and a salt of an alkaloid such as nicotine sulfate. In suchbentonitenicotine products about '7 to percent of nicotine is chemicallybonded to the bentonite and is neither volatile nor readily soluble. Theparticles may carry also up to about an equal amount of nicotine assulfate absorbed or adsorbed on their surfaces but not chemically bondedthereto, this portion of the nicotine being both soluble and slowlyvolatile even at room temperature. Such products are satisfactory withrespect to caking and are well adapted to certain uses as insecticidesbut are open to the objections that the portion of the nicotine combinedwith the bentonite is not readily available and the portion which is notcombined with the bentonite is volatile and the products must thereforebe transported and stored in air-tight containers. In my Patent No. 2343,359, I have disclosed a method of meeting this latter objection bybinding the soluble nicotine content of the products, i, e., that whichis not chemically bonded to the bentonite, by the use of a fixing agentsuch as tannic acid, tobacco dust, or lubricating 011.

Another powder material containing nicotine as an essential insecticidalingredient has been made by incorporating the nicotine into finelydivided alkaline tobacco and tobacco stem matem1; see my prior PatentNo. 2,343,360. In this product, however, the nicotine is purposely madereadily volatile and the product must therefore be handled inhermetically sealed containers.

An object of the present invention is to provide a nicotine insecticidematerial in dry powder form which contains a sufiiciently highpercentage of nicotine to warrant long-distance shipment, e. 'g. 10percent or more, preferably at least 14 percent, expressed as alkaloid,and which contains the nicotine in a readily soluble but nonvolatileform, and can therefore be handled in non-sealed containers such aspaper bags. Such a product must be reasonably free of the tendency tocake and must be sufficiently inexpensive to compete with otheravailable nicotine insecticide materials. Such a product isappropriately referred to hereinafter as dry concentrate.

I have found that such a nicotine product can be provided by combiningnicotine sulfate with finely divided tobacco material (leaf and/or stem)in fairly high percentage. e. g., 14% nico tine or higher, under thefollowing conditions: (0:) preferably use nicotine sulfate which issubstantially pure or at least free from gummy or tarry material; (b)combine the nicotine sulfate with the tobacco material under suchconditions as to produce a neutral to acid product; (0) combine thenicotine sulfate with the tobacco material in the presence of sufficientwater; ((1) dry the mixture of finely divided tobacco material andsolution of nicotine sulfate at elevated temperature.

In the product of the present invention the nicotine sulfate is notmerely carried by the finely divided tobacco material as extender nor isthe nicotine chemically combined to insoluble form as in the case ofbentonite-nicotine. It appears that the nicotine sulfate is convertedinto nicotine salts of acids that are naturally present in the tobaccomaterial in combination with inorganic bases, which nicotine salts aresoluble in water but are non-volatile, or held non-volatile by theirassociation with the tobacco material. Whatever may be the trueexplanation of the fixing of the nicotine in soluble but non-volatileform in the tobacco material the invention will be described hereinafteron the basis of a chemical transformation of the nicotine sulfate byreaction with the salts naturally present in the tobacco material, itbeing understood that other or additional factors may be involved.

The use of pure nicotine sulfate is not essential, but it is importantto avoid the presence of any impurity which would give the product atendency to cake.

Since the properties of the product apparently depend upon thecombination of the nicotine applied to the tobacco material with theacid radicals of the-salts naturally present in the tobacco materialandsince nicotine alkaloid is incapable of directly displacing the basesof the salts naturally present in the tobacco material, it is essentialthat the nicotine be applied to the tobacco material in the form of thesulfate or else that the tobacco material be first treated withsufficient sulphuric acid to combine with the bases in the tobaccomaterial thus releasing an equivalent amount of the acids naturallypresent :in the tobacco material to combine with the .nicotine added asalkaloid, and it is desirable to provide a slight excess of such acid.Interaction of the nicotine sulfate with the salts present in thetobacco material, e. g., potassium, sodium, and calcium salts of malic,citric and other organic acids .and hydrochloric acid, results upondrying in the formation of sulphates of the inorganic basesof thesesalts present in the tobacco material and of soluble but non-volatilesalts-of nicotine with the acids of the salts present in theto'baccomaterial. -Moreover, the presence of an excess of free acid inthe reaction mixture :safeguards against loss of nicotine byvolatilization during the drying of the product, as it prevents theliberation of nicotine alkaloid by the interactionof the nicotinesulfate' with constituents of some tobaccos which'have a neutral toalkaline reaction. The amount of such free acid need not be rigidlycontrolled in order'to prevent burning of 'foliage'whenitheiinsecticideis applied toplants, sinceinithe 'finalzproduct, the free acid is an"organic acid iorJamiXture of organic acids which, even in concentratedform, does not injure foliage. The limiting factor therefore appears tobe the total :organic acid content of the tobacco material.

I have demonstrated that the use of sufficient waterin the reactionmixture is highly important. For :instance, I have found that a product,made by mixinga nicotine sulfate aqueous solution containing 40%nicotine "expressed as alkaloid and 40% .water with .finely igroundtobacco stems in proportions "to yield a "dry product containingabout'lllpercent o'fmicotine as alka'loidand drying the mixture atISO-170 F, still contains a small amount "of (nicotine sulfate; asdetermined by extracting the product with alcohol, filtering theextract, evaporating the filtrate to dryness, extracting the driedresidue with water, acidifying 'the resulting solution with hydrochloricacid and adding barium chloride to precipitate the sulfate. .A similarproduct containing the same amount of nicotine made with the use ofnicotine sulfate aqueous solution containing 30 percent of nicotineexpressed as alkaloid and 60 percent water and extracted and tested inthe same manner was free of sulfate soluble in alcohol; while a productmade in the same way by substituting an equal amount of an inert carriermaterial, such as pyrophyllite, for the tobacco material gave a veryheavy precipitate of sulfate. Thus it is proven not only that sufiicientwater must be present but that tobacco material possesses an ability tobind 'the nicotine which is not posses-sedby, e. g., pyrophyllite.

My tests have shown that nicotine is quite volatile from nicotinesulfate when in the form of a thin film On an inorganic carrier; and thepurpose of my present process is "to convert the nicotine sulfate intoother less volatile salts of .be free from disease, especially tobaccomosaic, so as to prevent the transmission to other susceptible plants.While it would be possible to .heat .treat the tobacco material prior tousing it in .the'present process, it is advantageous to inactivate anytobacco mosaic virus which may be present by raising the temperature ofdrying in the present process sufficiently high and for a long enoughtime to accomplish this; i. e., a moist heat temperature of 212 F. forten minutes or more.

:A temperature of to F. is high enough to so soften the tobacco plantfibers and other constituents that the nicotine sulfate in the presenceof sufficient moisture flows or diffuses-into the plant cells for thecompletion of the reactions, but it is desirable to initially raise thetemperature of'the wet mixture to 212 F. for at least ten minutes indrying. This may be accomplished by drying in the absence of air, forexample by using a rotary steam tube atmospheric pressure dryer or arotary vacuum dryer. In the latter case the wet mixture would be broughtto a temperature of 212 F. under atmospheric pressure and "helditherefor 10 .minutes, when the pressure is reduced and drying proceeds at alower temperature as is customary in such equipment.

There must be enough water present .in the initial mix of tobaccomaterial and nicotine sulfate so that, through diffusion or "osmosisythenicotine sulfate comes into intimate contact with the natural salts ofthe tobacco material, whereupon the acid radicals'exchange. This leavesthe nicotine in -combination with hydrochloric, "citric, malic and otherorganic acids. Nicotine hydrochloride is in itself non-Volatile, but thenicotine salts 'of organic acids per se are as a rule more volatile thanis nicotine sulfate. These organic acidsalts of nicotine thereforeappear to be acid salts or complex salts from which nicotine is notvolatile or they are held within the plant cell walls or entangled inthepentosans of the tobacco material in a non-volatile form or both.Whether or (not thisis a true explanation of what actually happensjitseems to explain the established facts that my product contains noalcohol soluble sulfates and that the nicotine contained therein isnon-volatile.

'The water required may be added to the tobacco material prior to orafter the addition of the nicotine sulfate solution or as a part of thissolution. In adding enough'nicotine sulfate solution containing 40percent nicotine expressed as alkaloid to sufiicient tobacco material toproduce a final dry product containing 14 percent nicotine, enough wateris contained in the mixture to cause the desirable reactions to takeplace to a considerable extent; 'such would not however be the case if amuch 'lessamount of the same nicotine sulfate solution were added to thesame amount of tobacco material, say enough to pro duce a final productcontaining '3 percent or 4 percent of nicotine. I have found thatsufficient water is added to the tobacco material when the nicotinesulfate solution-contains 30 percent :nic'o tine as alkaloid, with acorresponding larger percentage of water, and is used in sufficientamount to produce a final product, containing 14 percent nicotine.

The amount of nicotine sulfate reacted with the tobacco must of coursebe proportioned to the natural salt content of the tobacco. I have foundthat when using the ground stems of flue-cured tobacco which contain ahigher percentage of salts than leaf material the nicotine content ofthe product will be stable, i. e., substantially nonvolatile at as highas 15 percent. If the nicotine content of the product exceeds about 20percent, some of it will be found to be volatile presumably due to thefact that not sufiicient salts are present in the tobacco material toreact with all of the nicotine sulfate and bind the nicotine asnonvolatile compounds;

It is of course within the scope of my invention to use an excess of thenicotine sulfate and to thus produce a product containing volatilenicotine along with the non-volatile nicotine. Such a product may beadvantageous for certain uses.

It is also within the scope of my invention to employ an excess ofnicotine sulfate and to safeguard the excess against vaporization by theaddition of a fixing agent as disclosed in my Patent No. 2,343,359; or,to simply add a solution of sulfuric acid to the tobacco material, thenmix it with a nicotine alkaloid solution in proportional amount assuggested above. When the free sulfuric acid is added directly to thetobacco material, this should first be diluted with most of the requiredwater. It is also within the scope of my invention to use other strongacids in place of sulfuric acid.

The product can be used alone as a dusting powder or suspended in soapsolution and used as a spray and it may be used in all sorts ofcompositions in which it may serve to supply all or part of theinsecticidal activity of the composition or all or part of the nicotineof the composition. It may for instance be mixed with extenders such aslimestone flour or with various clay materials or Pyrax or withadditional finely divided tobacco material or with other insecticidalagents such as cube or derris root (containing rotenone) pyrethrum, DDT,phenothiazine, calcium arsenate or with alkaline agents such as lime toliberate the nicotine in volatile form, or with copper and sulfurfungicidal agents, and the like.

The invention is illustrated by the following specific examples of thepreparation of the dry concentrate Example I Pounds Commercial nicotinesulfate solution containing 40% nicotine expressed as alkaloid and 40%water 40 Dry ground tobacco stems 76 Total wet mix 116 Moisture loss ondrying 16 Dry concentrate 100 This example illustrates the least amountof water which may be used in the wet mix to induce substantiallycomplete reaction, 1. e., about 20 percent of the weight of the drytobacco material used in the mix.

The nicotine sulfate solution and the tobacco stems are thoroughly mixedtogether by means of a dough mixer or a Simpson intensive mixer, and themixture dried by passing it through a rotary steam tube dryer whichinsures a tempera- 6 ture of at least 212 F. Of the material duringdrying. The dry concentrate thus produced contains 16 percent ofnicotine alkaloid in water soluble and non-volatile form. It is furtherground to the desired fineness, and packaged for shipment in paper orcardboard containers.

Example 11 :Pounds Pure nicotine sulfate solution containing nicotineexpressed as alkaloid and In this example the amount of water used inthe wet mix is about 36 percent of the Weight of the dry tobaccomaterial used, which proportion insures complete reaction. The oil isadded as an insurance against caking in the package. The mixing, dryingand grinding are carried out as in Example 1, giving a final productcontaining about 14 percent nicotine alkaloid.

Example III Pounds Commercial nicoting sulfate solution containing 40%nicotine expressed as alkaloid and 40% of water by weight 25 Dry groundtobacco material Water 20 Total wet mix Moisture loss on drying 30 Dryconcentrate 100 This example illustrates the method of preparing a dryconcentrate containing 10 percent nicotine by adding enough water to thewet mix independently of the nicotine solution to bring about thedesired reactions. The mixing, drying and grinding are carried out as inExample I.

Example IV 393 parts by weight of tobacco dust (leaf and stem material)were thoroughly mixed with 250 parts by weight of a 13 percent solutionof sulfuric acid. 100 parts by weight of an 80 percent solution ofnicotine alkaloid were added and thoroughly mixed. The wet mixture wasthen dried at a temperature of to F. and lost about 37 percent of itsweight as water. Very little of the nicotine content of the mixture waslost by evaporation during the drying operation. The product aftergrinding to a fine powder in a ball mill contained 16 percent ofnicotine and some free organic acid and was a free flowing non-cakingpowder.

The following are examples of a few uses of the dry concentrate:

Thoroughly mixed, this gives an insecticide dust containing 1 percentnicotine and 0.75%

rotencne which is effective against many vegetable insects and Europeancorn borer.

Percent Dry concentrate, 14% nicotine 20 Lead arsenate powder 20Micronized sulphur 58 Lubricating oil 2 This mixture when dusted onapple trees at intervals during the season is a good control for codlingmoth and scab.

The dry concentrate (14% nicotine) used alone as a spray at the rate of3 lbs. to 100 gallons of water, or at the rate of 1 /2 lbs. of dryconcentrate plus A2 gallon of summer spray oil to 100 gallons of waterproduces an effective spray for the control of codling moth and certainother insects on apples.

Percent Dry concentrate (14% nicotine) 50 DDT 12.5

Pyrophyllite 37.5

The above mixture used as a spray at the rate of 3 lbs. to 100 gallonsof water is a safe and effective control for codling moth on apples.

Percent Dry concentrate, 14% nicotine 14 Calcium arsenate powder 8Hydrated lime '(dry) '5 This is a combination dust which fits the cottonfield. When applied as a dust at intervals during the growing season atthe rate of 7 lbs. to 10 lbs. per acre it efiectively controls both bollweevil and cotton aphis.

Percent Dry concentrate, 14% nicotine 29 Hydrated lime (dry) 71 likewisetrue for all of the dry mixtures cited above; and also because there isno immediate liberation of free nicotine in the dry mixing of hydratedlime and dry concentrate. This dusting mixture, 1, may thus bekept inbags, or even in open containers until needed. This is also true for thecotton dust, Example 6. When such a dry mixed dust, i. e., onecontaining dry concentrate and a dry alkaline material such as hydratedlime, is applied to plants it takes up en0ugh moisture from the foliageor surface of the insects, on account of dew, etc., to cause a reactionto take place liberating the nicotine iromits salts as the free alkaloidwhich is the most toxic form for killing. aphids.

I claim:

1. Process which comprises uniformly mixing finely divided tobaccomaterial with nicotine sulfate in quantity suflicient to supply at leastabout 10 parts by weight of nicotine expressed as alkaloid for eachparts by weight of tobacco material in the presence of at least about 20parts by weight of water to each 100 parts by weight of tobacco materialunder neutral to acid conditions and drying the mixture at a temperatureof at least about F.

2. Process as defined in claim 1 wherein the temperature of the mixtureis raised to at least 212 F. for at least 10 minutes during thedryingoperation.

3. A new product consisting essentially of whole tobacco material and atleast ten percent of added nicotine calculated as the free alkaloid onthe dry Weight of the tobacco material combined with the tobaccomaterial in substantially non-volatile but water soluble state preparedby the process defined in claim 1.

ROBERT B. ARNOLD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,731,678 Mewborne Oct. 15, 19292,007,123 Dunn July 2, 1935 2,139,340 Hunter Dec. 6, 1938 2,228,096Tisdale Jan. 7, 1941 2,343,360 Arnold Mar. 7, 1944

